WEST LAFAYETTE, Ind. -- It's the environmental equivalent of turning a sow's ear into a silk purse -- Purdue University researchers have developed a process for making topsoil from coal ash, yard waste and industrial byproducts.
"There are many potential benefits to this project, including the long-term economical and environmental management of two so-called waste products -- coal ash and industrial byproducts," says Joseph Mikesell, director of utilities at Purdue and one of the participants in the soil-making project.
Jody Tishmack, ash management coordinator for Purdue Physical Facilities, says the combination of minerals from the coal ash and the nutrients in an organic-rich industrial byproduct makes a very effective soil additive.
"Mixing this material with poor-quality soil -- even sand and gravel -- creates a man-made topsoil that in preliminary laboratory tests outperformed local topsoil in terms of yield," she says.
The main ingredients in the soil all come from Purdue and the surrounding area. The coal ash comes from Purdue's Wade Utility Plant, which burns Indiana-mined coal in a clean coal combustion unit. The organic material, which also is used on farmland as a fertilizer, is a nontoxic byproduct left over from the manufacture of antibiotics at two Eli Lilly and Co. plants -- Tippecanoe and Clinton Laboratories. The yard waste, containing "friendly" bacteria that break down the organic material, is supplied by a local composting operation.
The main uses for the soil are for reclamation of Purdue's gravel pit and campus landscaping projects, but Tishmack says coal companies and other industries could use it to reclaim areas depleted of vegetation by industrial use.
"There are a number of sites, such as coal mines and gravel pits, where land has been
depleted," she says. "To reclaim these sites quickly with vegetation requires nutrient-rich
topsoil, and we can't afford to take that away from farms. In addition,
Contact: Amanda Siegfried